The long-range objective of the proposed research is to refine, evaluate, and disseminate an Internet-based intervention to prevent eating disorders (EDs) and comorbidities in college-age women. EDs are highly prevalent among college women and can lead to serious psychological and medical consequences. In previous work, we have shown that an Internet-based intervention can reduce onset of EDs in select subgroups but, given its focus solely on weight/shape concerns (WCS), the intervention had little impact on comorbidities common to this population. We have also identified three risk factors which, when combined with the presence of WCS, indicate very high risk for an ED: a history of depression and/or exposure to critical comments about weight/eating from teachers/coaches/siblings and/or low-level compensatory behaviors (e.g., vomiting and purging). The rate of onset of EDs in women presenting with these risk factors is greater than 30% over 2 years, compared to less than 4% in participants presenting with WCS only. We propose to enhance our previous Internet-based intervention to address these risk factors, and to sustain the effects of the intervention, by including affect improvement and regulation modules, and by adding a maintenance component, respectively. Our primary hypothesis is that, compared to a usual care group, participants in the intervention will have a significantly lower incidence of EDs at two-year follow-up. We expect to lower the incidence from an anticipated rate of 30% to 15%. We also hypothesize that the intervention will significantly reduce WCS, unhealthy weight regulation behaviors (e.g., vomiting, laxative abuse), and dietary restriction while improving mood, coping skills, and emotion regulation. We expect reductions in the combined incidence of depressive, anxiety, and substance use disorders. Moderators and mediators of potential treatment effects will be examined as well. In order to further illustrate our ability to disseminate a low-cost program to universities, we plan to implement and examine the sensitivity and specificity of an Internet-based screen to identify women at risk for EDs and to provide our original prevention program to women with high WCS only. To achieve these aims, 200 college-age women with both high WCS and at least one of the very high risk factors will be randomized to the intervention or a usual care group and followed for at least two years. 250 women with high WCS only and 100 women with low WCS will be recruited for the purpose of screening and dissemination aims. The enhanced intervention, which will be provided for 12 weeks, followed by four maintenance sessions provided over the subsequent eight months, translates findings from basic clinical studies into a disseminable intervention. If effective, the enhanced intervention provides an easy and inexpensive method to reduce EDs and ED comorbidity in college-age women PUBLIC HEALTH RELEVANCE: Eating disorders are common and disabling problems among college-age women. Research has identified a group of college age women at particularly high risk for eating disorders and co-morbid conditions. The purpose of this study is to determine if an internet-based intervention can reduce the onset of eating disorders among this highest risk population and also reduce co-morbidity. If so, this finding, combined with our previous research would have a major public health impact on reducing eating disorder rates.